The subject invention relates generally to photographic printers and more specifically to photographic printers including apparatus for measuring the reflective density of reflective patches.
In the course of printing photographic negatives and developing the corresponding prints it is often desirable to measure the reflective density of photographic prints and/or reflective test patches. To control a photographic paper processor, for example, it is often necessary to measure the reflective density of a strip of reflective patches of known exposure, i.e. the paper processor control strip. To analyze the performance of a photographic printer, it is often desirable to measure the reflective density of selected photographic prints made with that printer.
U.S. Pat. No. 4,526,462 to Hope et al. shows a photographic printer including a print test probe connected to a microprocessor and activated by a user to measure the light reflected off of a print. The microprocessor is subsequently used to calculate the reflective density of the print. Hope et al. suffers, however, from the disadvantage of requiring manual positioning of the probe by an operator for each measurement. Further, the patent does not appear to show any automatic positioning of the filters necessary to perform the reflective densitometry measurements. Presumably, the positioning of such filters will require manual intervention by the operator.
U.S. Pat. No. 3,462,221 to Tajima et al. shows a photographic printer and processor including a light sensor positioned to measure the light reflected off of processed prints. The light sensor is connected to a control device, which is subsequently used to control the printing process and processing conditions. Tajima et al., however, suffers from the disadvantage that it is only capable of measuring the reflective density of the paper present in the processor, and does not provide the ability to measure, for example, an externally provided film process control strip. Further, the patent teaches only the measuring of black and white prints, and does not make any provisions for measuring the reflective density of color prints or reflective patches.